Telephone system



Feb.'9,1926. 1,572,587

S. B. WILLIAMS TELEPHONE SYSTEM Feb. 9 19m, 1,572,587

v s. E. WILLIAMS TELEPHONE SYSTEM l I I t l I I Filed April 21, 1924 l,1o sheets-sneeta l l `l l I l |v Il lIl .by my Feb. 9 1926.

s. B. WILLIAMS TELEPHONE SYSTEM Filed April 2l, 1924 10 Sheets-Sheet 4 Feb. 9,1926. 1,572,581

S. B. WILLIAMS TELEPHONE SYSTEM Filed April 21, 1924 1o sheets-sheet s /m/emor.' Jamel /IW//dms by fif.

Feb. 9 1926. 1,572,587

- s. B. WILLIAMSA y TELEPHONE SYSTEM Filed April 21, 1924 l 1o sheets-snm.U s

Feb. 9,1926. '1,572,587

TELEPHONE SYSTEM Filed April 21, 1924 lO Sheets-Sheet 7 S. B, wlLLlAMS TELEPHONE SYSTEM Filed April 21, 1924. 10 Sheets-Sheet a Feb. 9,1925, A 1,572,587

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,by My Feb. 9 1926. 1,572,587

S.B. WILLIAMS TELEPHONE SYSTEM Filed April 21, 1924 1o sheetsQsheet e /m/enaf: Samuel B W/Y//dms I ,by m AW Feb. 9 1926.? 1,572,587

S. E, WILLEAMS TELEPHONE SYSTEM Filed April 2l, 1924 10 Sheets-Sheet 10 Patented Feb. 9, 1926.

PATENT OFFICE.

SAMUEL IB. WILLIAMS, OF BROOKLYN, NEW YORK, ASSIGNORTO WESTERN ELECTRIC COMPANY, INCORPORATED, F NEW' YORK,N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application filed April 2.1, 1924. Serial No. 707,795.

To all whom t may concern:

lle it. known that I, SAMUEL B. VILLIAMS, a citizen of the United States of America, residing at Brooklyn, in the. county of Kings, State of New York, 'have invented certain new and useful Improvements in Telephone Systems, ot which the following is a full, clear, concise, andeXact description.

This invention relates to telephone systems, and particularly to systems of the character in which automatic switching equipment is employed for thev establishment or'l connections.

in systems employing machine switches oi' the coordinate type in which link circuits are involved and consequently a comparatively large number of contacts, it is desirable to make a. test to ascertain the condition ot' these contacts whenever a connection is established to a subscribers line. It the switch is operating properly and all of the contacts are closed, then the operation may be proceeded with and ringing current applied tothe subscribers line. However, if certain of the switch contacts fail to close properly and this abnormal condition is detected, the ringing' current may be withheld iirom the ysubscribers line and a signal given to an operator or an attendent.4 A

it is, therefore, the obj ect of this invention to perform a test of the talking circuit established through the switchesV -ot' ascertain whether or not said circuit is in prop-er condition.

A. feature of the invention consists in establishing a test path which includes the talking circuit extended through the contacts of the switches to the subscribers line, without including1 said line, for the purpose of determining the continuity ot said talking circuit.

A further feature relates to the provision, in a system having switches and switch controlling markers of a test circuit comprising the trunk leading to the switches and the contacts of said switches, said test circuit also including the source oftalking battery in the trunk and responsive means in the associated marker. v'

Another feature consists in the provision ot a signal associated with the switch controlling apparatus and which becomes effective in case the test reveals an unstandard condition together with means for preventing 1further progress of the connection.

Referringl to the drawing, F l to l0, inclusive, when taken in the order illustrated Ain Fig. 1l disclose a portion of a telephone system. embodying` the features ot this invention.

Fig. 1. shows an interoiice trunk incoming from a distant office together with certain controlling apparatus associated therewith.

Fig. 2. shows an incoming selector switch in which incoming trunks terminate.

F ig.` 3. shows a# portion of one'of the final or connector switches in which the called subscribers lines terminate f Fig. 4 illustrates diagramn'iatically a sender selector switch and also a portion oi one ofthe common register senders.

Fig. 5. shows a sender connector for connecting the registersenders to the markers.

Figs. `G and 7 illustrate one of the common markers, the function of which is to control the incoming and iin-alswitches.

Fig. 8 shows an incoming frame connector for connecting the markers tothe frames of the incoming selectors.

Fig. 9 shows a translator connector for the purpose of connecting any of the markers to any of the final translators.

Fig. l0 shows one of the inal translators, the function of which is to cooperate with the marker to control the iinal switches.

General description of the circuits cmd .apparata-s.

The Atrunks which lead from distant otiices to the oiiice illustrated in the drawing terminate in vertical rows of contactsl or'1 incoming selector switches such as the switch 200. The trunk 100 illustrated, for example, appears in the vertical row 201 of the switch 200. Other similar trunks also, occupy the same and other vertical rows otI this switch. The incoming trunks also appear in vertical rows ot contacts oit the sender selector switches 400.

For convenience in the vmethod ofcontrolling the switches, the incoming selectors 200 are divided into a number of groups. The trunks which appear in the incoming selectors ot a given group are segregated in kone or more vertical rows of contacts on the sender selector switches 400. By this means whenever a vertical magnet controiling a given row of contacts on the.l sender selector 400 is operated, it recordslan indication in the sender, identifyingr the particular vgroup of incoming selector switches to which extends the trunk involved rin the connection.

rl`he incoming selectors 200 have access to groups of trunks which appear in vertical rowssuch as the row 204, which trunks lead to final o-r connector switches 300, which in turn, have access to the called subscribers lines. -Une oi these trunksi213 is shownin full, appearing in the vertical row of contacts 301 of the connector` switch 300. A number of called subscribers lines are also illustrated appearing invertical rows of contacts 303 land /1.

The incoming and iinal switches 200 and 300l and the sender selector switches 100 are of the coordinate type such as generally shown and described inthe copending application of J. N. Reynolds, Serial No. l136, 367, tiled July 21, 1921Patent No. 1,507,140 issuedSepteinber 2,1924 and in the patent to Samuel B. lVilliams No. 1,517,331, issued December l2, 1924. The operation of the switches and controlling- `apparatus illustrated in this case is similarto that described more in detail in my copending application y Serial No. 701,006, liled March 22, 1924.

The subscribers lines considered as called lines are divided into a suitable number of groups. If-it be assumed `that the exchange comprises 10,000 lines, it may be convenient to divide these into twenty groups of 500 lines each. For each group of 500 lines a suitable number of connector switches 300 are .provided or y:making connection therewith. Furthermore, each group of'500 lines is provided with a final translator 1000 which is common to all oi the'r connector switches of thev group and serves to selectively operatethesame. The translator 1000 is made up of three multicontact relays.

1003, 1012 and 1013. The first two o'these relays each have 4contacts representing 200 different subscribers lines, andthe third relay 1013 has contacts representing 100 subscribers lines. The grid wires with which these relays make Contact are divided into four di'iierent sections, and four relays 1014, 1015, 1016 and 1017 each-corresponding yto a sectionaregalso provided. These relays are controlled from the hundreds and units registers 601 and 603 of the marker in accordance with whether or not the hundreds and unitsdigits are less than 5 or greater than 41. For example, if the hundreds digit is greater than 4 and thefnnits digit is less than 5, the relay 10141 is operated, whereas if both hundreds Vand units digits are greater than il. thek relay 1015 is operated.

'By selecting one of the relays 1008, 1012 or 1013 inaccordance with the setting of thel hundreds register 601 and by selecting o ne ofthe relays 1014. to 1017,1n1accordance with the combined setting of the hundreds register 601 and the units register 603, a selecting circuit depending upon the setting of the tens register 602 is extended through the translator to choose the proper vertical operating magnet on the connector switch tended through the sender selector switch 4100 to an idle register sender, `the impulse receiving relays L102, 403Y and 404i are included'in series with the trunk and respond to codes of impulses transmitted thereover in accordance with the desired designation. These relays control a set of registers, not shown, upon which Ithe different `digit-s ot the desired number' are recorded. Attentim recording yor' a designation, the sender is associated with the marker by means ot the sender connector 500 andthe .number vrecorded on the sender registers is transferred to the corresponding registers '600, 601, 602 and 6030iv the marker. Fo an understand ing of the manner in whiclrthe sender rcsponds to cod-e impulses transmitted over the incoming truiilnfreference is made vto the patent toS. B. lVilliainsfand E. S. Gibson, No. 1,543,967,grantedJune 30, 1925.

lVhile the present invention has been'cmbodied in '-a `'system involving rinteroilicc trunking, it will be understood that it is also applicable't-o local switching equipment and-that Athe trunks which terminate inthe incomii'igselectors 200 may be trunks incoming frein switches in the local oHice. Referring again to the markers, these mechanisms are arrangedito be connected to the incoming selector switches 200 by rmeans ot the trame connectors 300. Each frame connect-or '300 serves to connect any of the markers to any of the incoiningswitches 200 in a given group.

y Detailed descrptz'on of `the operation 'It will be assumed that-a connection which has been extended over the-interofiice trunk 100 is desired to be'completed to the called subscribers line 310. lVhenithe trunk circuit is closed at the distant oiiice a circuit is completed for operating the relay 103, traceable from battery through the left winding lof 'said relay, lettcontact of relay 102, upper let't winding ot repeating coil 106, upper outer back contact of relay 101, thence overthe trunk circuit 100 and rcturning through the lower outer back contact ot relay 4101, lower left winding of coil 106, Contact of relay 102, through the right Winding yof relay 103 to ground. Relay 103 operates the relay 401 in a circuit troni ground through the left contact o't relay 103, inner upper contact ot relay 101, inner upper contact of relay 108, Winding et relay 401 to battery. Relay 401 initiates the operation of the sender select-or switch 100 which functions to extend the trunk 100 to an, idle register sender. During the operation of the sender selector 400 ground potential is placed on the conductor 115 which leads through the inner back Contact ot relay 411, Winding of the selector holding relay 110 to battery. Relay 110 operates and locks through the contact oit relay 100 to ground. Relay l10 operates the relay 111. .Relay 111 opera-tes the relay 101 in the following circuit: Battery, through the Winding oit relay 101, conductor 111, through the Aswitch 100, conductor a15, inner -liront contact et relay 111, winding out relay 112, to ground at the outer contact el: relay 111. Relay 101 releases the relay 101. ltelay 101 operates the sloW-to-release relay 10-1, and opens the circuit of relay 103, lerniitting this latter relay to release.

The apparatus is new ready to receive code inipulses and relays 402, 103 and40fl respond to these impulses to set up the record on the registers of the sender. fitter the record has been recorded relay 11T operates and initiates the yoperation et the sender connector 500 by causing' the operation of' relay 501. The circuit for `this purpose inay be traced lroin ground through the ccntact of relay 1117, back contact of relay 420?. back contact et relay l108, contact et relay L109, conductor 418, lower Winding oitrelay 501 to battery at the contact ot relay 502. Relay 501 locks in a circuit troni battery through the Winding of relay 502, upper contact and Winding ot' relay 501 to ground over conductor 118. Relay 502 also operates in this circuit and prevents subsequent eperation of another relay siinilar to relay 501, in ease a second sender'atteinpts connection to the marker. Relay 503 noW operates in a circuit iroin battery through its Winding, lower contact oi relay 501', outer Contact of relay 50aL to ground at the inner right contact of relay 502. Relay 503 locks through its own Contact to -ground at the lett contact o1 relay 502. Relay 502 operates relay 506 which relates to the-iirst idle marker (it being assumed that the' marker represented by relay 500 is husy at the time.) rlhe circuit for relay 506 inay be traced frein ground through the inner right contact ol ,relay 502, inner back contact et relay 50st,

lower :trout contact oit relay 510, lower back Contact of relay 509, lower bach contact 0i' relay 505, lower Winding of relay 500 to battery at the upper contact et relay 508. llelay 500 locks in circuit troni battery through the Winning ot relay 508, upper Winding and contact-*of relay 506 to ground at the contact oi" relay 502. Relay 508 also operates in this circuit. `telay 505 yoperates relay 5011 in a circuit troni battery through the Wir ling oit the latter ot relay, upper contact ot relay 506 to ground at the contact et relay 508; The inulticontact relay 507 is next operated to entend the various leads troni the sender to the selected idle inarlrcr.` 'lhe circuit for relay 50in may be traced troni battery through 'the Winding thereof. middle upper Contact of relay 500 to ground at the inner Contact oitI relay 508. 505ialso operates inparallel with relay 50'?.

As soon as the sender is connected to the inarlrer the holding relay 700 is operated in a circuit iroin battery throughthe Winding thereof, conductor 701, thence througlii the sender connect-or 500 to ground in the associated sender. Relay 700 locks in a circuit through its Winding and contact right back Contact of relay 7053 to ground at the inner left contact ont relay 7041.

The record of the thousands, hundreds, tens and units digits and also a record ci the particular group of incoming switches involved are new transferred from the sender to the marker. First considering the record of the group oft Iincoming selectors to which the tunlr 100 extends, it will be notedk that this trunk appears in the vertical row of contacts in the sender selector switch 100 which is controlled bythe vertical niagnet 120. fit the tinie magnet /120 operated in extending the trunli tothe sender, lit closed an obvious circuit ttor relay 421 in the sender. ltelay 121 operates and locks in any desired inanner. Thereafter when the sender is associ ated with the niarlier the relay 121 causes the operatic-n oitV the relay G06 in the niarker by means of a circuit traceable from ground through the right front contact of relay 121, conductor 122, through the connector 500, winding of relay 000 to battery. Relay G00 operates and selects the traine connector 800 as the one to be operated l'or connecting the inarlter to the proper incoming switch 200 in the proper group oit incoining switches.

1t may be assumed that the numericalrecord set up Iin the sender shown in 4 is one which when transferred to the registers of the niarlrcr illustrated in llig. 0 causes the operation ci the following relays: relay 010 et the thousands register 600, relay e123 of the hundreds register G01, relays 015 and 017 o1l the tens register 002 and relay 020 of the units register'lltll.

is is desc "ibo-fl in copending,application Serial No. i03,802,'iiled llpril 1, 1921, all oi the remaining relays of the inarler which do not correspond to operated register relays in the sendcrare cnergitezil `nionientarily. ils soon as all et these relays have been energized a circuit is completed from RelayA 710, right back contact of relay 711, con- Cil ductor 716,' inner right contact otrelay vT12, conductor 713 to ground at the middle right contact ot relay 700. Relay (340 operates the relay G41 which locks through its lower con tact to the grounded conductor 624-. Upon the loperation of relays @l0 and G11, all ot the momentarily operated register relays ot' the marker are re eas ad and only 'these relays which represent the designation remain energized. Relay (3l-0 Ithereupon releases. The relay G25 is now operated to subsequently determine the selection of a connector 900 for connecting the marker to the proper one of the twenty (litlerent linal selectors. The circuit for this relay maybe traced trom battery through the winding thereof, inner rightback Contact of relay G15, conductor 626, Aconductor G27, upper front Contact ot' relay (Sll tothe grounded conductor 024. lVith rela-y 606 operated a circuit is closed for operating the frame connector start relay 8041 which is individual to the marker illustrated. This circuit may be traced from battery through the winding of relay7 804e, conductor 807, right back contact of relay 605,

f right-v front contact ot relayl G06 to ground on conductor G2G. Relay 804C operates the relay 805 in a circuit traceable from b attery through the lower winding ot' krelay 805, front contact ot relay 8071, back contacts of relays similar tol relay d, leftbackcontact of relay S02 to ground at the varmature of relay 803. Relay S05 operates the slow release relayv80l in a circuit from battery through the winding of the ylatter relay, right contact oit relay S02, lower contact oi'f relay S05, conductor 809, outer right Contact of relay `712, to the grounded conductor 713. Relay 805 being slightly slow to rele-ase, does not retract its armatures while relay S03 is operating. Relay 803 operates, and a locking circuit is closed )for relay 805 from battery through the upper winding and 'contact thereof, over back contacts of preceding similar relays, winding oit relay 802 to ground at the front contact ot relay S03. Relay 802 operates in this circuit and relays 805 and 802 are locked in a new circuit leading through the right front contact of relay 802, lower contact of relay 805 to ground on conductor 809. Relay 80?) releases after an interval. Upon the release ot relay S03 the multi-contact relay 806 is operated in a circuit from battery, through the winding of relay 80G, front contact ot relay 805, left back contact of relay 808. Therelay'SOG is individual to the marker shown and serves to connect the conductors from said marker to the grid Wires of the frame connector 800.l

The next operation to take place is the energization of the vertical magnet 209 controlling the vertical row of contacts 201A in the incoming selector switch 200 in which appears the trunk 100. T he preparatory circuit for this purpose may be traced from grounded conductor S09, lower contact of relay 806, conductor 811, normal contact ol" relay 71a-, conductor 715, through the connector 500, vconductor lhthence through the sender and sender selector 100, conductor 421-, winding ot relay 111 to battery. manner in which this circuit is completed from the marker through the sender connector and thence through the sender and sender selector switchis lfully described in my Patent 1,517,331, granted December 2, 192i. The relay 111 operates the vertical magnet 209 in a circuit from battery through the winding ot said magnet, conductor 221 to ground at the left contact of relay 111. The magnet 209 rotates the bar 207 and prepares the contacts in the vertical row 201. The multi-contact relay 801 individual to the incoming selector switch 200 is also operated in a circuit from battery through the winding o't said relay, conductor 812 to ground at the right contact of relay 111. Relay S01 connects the grid wires ot the trame connector S00 to the leads extending to the Aincoming switch 200. Y

rl`he magnet 209 operates the relay Tl-fl in a circuit from battery through thev winding of said relay, conductor 717, through the frame connector 800 to ground at the contact of magnet 209. Relay 7141 closes locking circuits `tor the magnet 209 and relay 801. These circuits may be traced from battery through the windingk and contact of magnet 209 and in parallelfrom battery through the winding and contact of relay 801, thence through the connector 800, conductor 814, contacts ot' relay 714, conductor S11, contact ot relay 806, conductor 818 to the grounded conductor `809.

The next step in the process is to associate the marker with the particular one of the several linal translators which has control over theV group of linal switches reaching the group of 500 lines containing the called line 319. rlhe selection of the proper inal translator is determined by the hundreds register 601. Therefore, when the relay S05 operates a circuit is closed for operating the relay 908 which is individual to this particular marker at the connecting device 900. The circuit for this purpose may be traced from ground through thebaclz contact of relay 803, lett front contact of relay 802, uppermosty contact ot relay 805, confront Contact of relay S02 to ground at the ductor 810, inner upper contact otrelay Gal,

lll)

right back contact 'ot relay 611, outer right front Contact of relay 610, inner Contact of relay 625, conductor 623, Winding of relay 908 to battery. Relay 908 operates relay 905 in a circuit through the left Winding ot the latter relay, front contact of relay 903, right contact or" relay 906 to ground atthe hack Contact ot slow-to-release relay 907. Relay 905 operates relay 907 in a circuit from battery through ther Winding et the latter relay, lett Contact ot relay 906, left contact ot relay 905,- conductor 910, right back Contact oi relay 711 to the grounded conductor 716. Relay'905 being slightly slouT to release,rdoes not retract its armatures While relay 907 is operating. Relay 907 operates and a circuit is closed troni battery through the right Winding and contact ot relay 905, winding of relay 906, to ground at the contact of relay 907. Relay 905 locks and relay 906 operates in this circuit, thereby releasing relay 907. Relay 907,. in releasing,operates the multi-contact relay903 in the llovaiing cir! cuit: battery through the Winding' ot relay 903, rightlront contacts ot relays 90.5 and 906 to ground at the back Contact of relay 907. Relay 903 operates its contacts and extends the leads froin the marker through to the translator shown in Fio. 10.

The operation et thenal translator will next be discussed. Since the hundreds digit is such that the relay 613 of the register 601 is operated, a circuit is completed for operating the inulticontact relay 1003 of the translator 1000. This circuit may be traced troni battery through the Winding ot4 said relay, outer rie'ht contact of relay 1018, through the connector 900, conductorA 911, inner right back contact of relay 612, right 'front Contact of relay 613, right back contact of relay 614 to ground over conductor 626 as previously traced. nasniuch asthe units digit is suoli that only relay 620 of the register' 603 is operated, a circuit is completed 'for operating the relay 1017. r his circuit inay be traced 'liroin ground through the right back contact oit relay 623, conductor 630, connector 900, through the winding of relay 1017 and returning through the connector 900, conductor 912,' outer right bach Contact ot relay 615 to ground over conductor 626. f

Since the tens digit is such that both relays 616 and 617 are operated a circuit is coinpleted as tolloivs for operating the vertical magnet 316 on the connector switch 300 which relates to the row ot contacts 303 in which appears the called iine 319: Frein ground over conductor 626, vthrough the inner back cont-acts ol relays 619 and 618, inner right front contacts of relays 617 `and 616, conductor 631, connector 900, conductor 913, contact of relays 1017 and 100:8, conductor .1019, -yyjnding of magnet B16/Winding ot relay 328 to battery. Magnet 316 rotates the bar 320 and prepares the contacts in thevertical row 303.

Magnet 316 operates the relay 1001 which is individual to the final connector trarne 300 and which serves to connect certain leads in the translator to said trarne.y The circuit for this purpose may be traced from battery through the Winding of relay 1004, `back contact ot relay 1025, conductor 1026, inner eontact o-inagnet 316 to ground over conductor 1019 as previously traced. Magnet 316 and relay 10011 lock in circuits `from battery through the Winding and inner contact ot magnet 316, thence through the lower contact of said inagnet and in parallel thereto frein battery through the Winding of relay 10011 and thence over conductor .1026, through the lower contact of magnet 316, and thence over conductor 321, conductor 703, rightv back contact of relay 7,07, `outer right back Contact of relay 706, outer-right back Contact of relay 710, right back contact of relay 711 to the groiiinded conduotorp716.

Inasnnich as the units digit determines the appearance ot the Wanted line in the seetion 311 or' the switch 300, it will be necessary to operate the 1nulticontact relay 1006. The circuit `for this purpose may be traced frein battery through the 1Winding of said relay, through the connector 900, conductor 914C, inner right back Contact ot relay 621,

right front cont-.ct of relay 620 to the grounded conductor 626.

ylhe connection of the inarker to the group of trunks interconnecting the incoining and connector switches will now be described. Since there are a nuinber of groups of trunks leading freinV theinconi-ing switches to the :tina-l switches, it is essential that the marker be eonneotedto the particular group which leads to the final selector 300'containingthe called subscribers line. The identity oit the group of trunks may be had `from the incorning frame connector 800 and the'identity oit the group of linal switches may be had from the translator 900. Accordingly, the inulticontact relay y315 is operated in a circuit from battery through its Winding, back contact ot relay 816, conductor 319, through the connector 900, conductor 916, through the traine connector 800 and returning over .conductor 703-to ground. Rclaytll is individual to the group of trunks including [he trunk 213 and serres to connect the inarker testing equipment to the sleeve conductors of these trunks. Relay 815 .operates the relay 919 in a circuit 'lroin battery through the Winding of the latter relay, thence through the connector 90,0 to ground at the Contact of relay 815. f y

The next step is to test the trunks and links and also the called subscribers line. rthe marker is provided with a series of test ing relays 7.20 cai deine' a .sufficient new" leo ber of these relays for testing the horizontal links of the incoming selectors, the trunks,

outgoing therefrom ,and the horizontal links of the final selectors. rI he double Wound relays 721, 722, 723, etc., each have a Winding for testing the horizontal link in the incoming switch and a Winding for testing the trunk which has access tol such link. Either winding is sutlicient' to operate the relay and both windings will also operate the relay. Therelays 724, 725, etc. pertain to the corresponding horizontal links in the connector switch. Assume, first Athat the link 205 of the incoming switch200, the first trunk213 and the link 305 off the connector switch are all simultaneously busy. A. circuit is, therefore, completed vfrom battery through the left Winding of test relay 721, innermost back contact of' relay 727, through the connector 80,0, conductor 1020 to the grounded sleeve conductor'ot the link 205. Another circuit is vclosed from battery through the rightwinding ot relay`721`, next to the inner back contact of relay 7 27, inner right back contact of relay 728, conductor 729, through the connector 900, conductor 922', contact of the relay 815, conductor 822 to the grounded sleeve conductor of trunk 218. The link 305 also being busy a circuit is closed for operating relay 7 24 which may beltraced from' battery through the outer lett Contact ot relay 730, Winding ot relay 724, contacts of relay 919, conductor 023, connector 900, conductor k918, Contact ot relay 1006, through the connector 1002, conductor 1029 to the grounded sleeve conductor ofthe busy link 305. Hadthe link 205V and the trunk l213` been idle the busy condition ot link 305 would cause the operation of relay 7 24', which in turn, Wouldcause the opera-` tion of relay 7 21.l The operating circuit for relay 721 in this case may be traced through its vright Winding, inner contact of' relay 7211, outer right' back contact of relay 7 30, conductor 732 to ground at the inner right contact of relay 700. The relay 721, in operating, extends the start conductor 7 33 on to the next testv relay 722 Ywhich may or may not he energized according to the condition of the corresponding links and trunk;

It, however, the first link 205,' trunk 213 andthe link 305 are `all idle at the same time, the test relayv 721 remains deener gized'. Themagnet 212' which controls the Vertical row of contacts 20st, in which* apf pear the trunks of the selected group, is also operated atfthis time. The` circuit tor this purpose may be Vtraced from battery throughithe Winding of said magnet, conductor 215, through 4the connector 800,-conductor 8241, through the connector 900, conductor 924 contacts orc relay 81.5, conductor 820, contacts otrelay 100G, contacts of re'- lay 1004, conductor 1021, connector 900, contact .of relay A919, conductor 708 to ground,

. contacts The magnet V212 rotates the bar 216 and prepares thejcontacts in the vertical row 20st.

The magnet'212 operates the relay 780 in a circuit traceable from batterythrough the winding of said relay, Contact ot relay 701:5, conductor 731, through the connector 800, conductor 222, contact of magnet 212 .and returning over conductor 223, through the connector 800 to ground over conductor 809. Relay 7 30 operates the relays 727, 7 28 `and 7 05. VThe circuit for this purpose may be traced from the grounded conductor 7232, right outer front contact of relay 7 30, thence in parallel through the winding ot relay 727 and'tlirough the inner right contact o1 relay 710, conductor 713, back contact ot relay 735, back contact of relay 721, winding of rela-y 728, winding of relay 705 to battery. p

During the foregoing operations a test is also'made to ascertain the condition oit the called'subscribers line. At the time the connecting devices `1001 a-nd 1002 are operated, the'magnet 310 is energized in a circuit from battery through its Winding, thence throughcontacts of connecting devices 1002 and 1001 to the grounded conlductorf708. Magnet 310 operates the common test link 307 which makes connection with the sleeve conductor ot' the called line 31S). l/hen relay 730 later operates a test circuit is closedtrom battery through the winding of relay 711, trontronact of relai,v

7230, middle right back contact ol relay 710,

left't contact ot relay 730, conductor 7137, connector 000, conductor 10i-l2, connector 1002,-co1niluctor over the les( linksI 307 to the sleeve conductor ot the line`2'l10. suining the line 51010 be idle .at the time, relay 711 tails 'to operate.

lilith the test relay 728 operated as aboeo explained a circuit' is closed .tor operating the Vertical magnet 318 on `the ii'ial'seleistor switch inl the contacts ot which the trunk 21.25 appears. This circuit may betraced from the grounded conductor 708, (hence tl rough the outer right contact ot relay 728, coi'idl'ictor 730, Contact oit relay 010, connector 900, conductor 020, through the of the relay 815, connector 1002, winding ot magnet 318m battery. Magnet- 318 rotates the bar 313 and prepares thecontacts in the vertical row 301. The magnet 318 also causes the operation oit tho horizontal magnets 217 and 300. 'the circuit for magnet 217 may be traced from battery through the right winding of said magnet, conductor 218, contact of relay 801, contact of relay 806, conductor 820, outer lett `,contact of relayv 728, conductor 740, connector 900, conductor 932,' connector 1002, Contact of magnet 318, conductor 1026, contact of magnet 316 to the grounded conductor 321.k Magnet 217 operates the bar220 and establishes connection between nector 000, conductor 9341-, contacts ot relay l19, conductor 03?, outer lett Contact ot reley 720 und thence te ground over conductor Tg1() us alcove truccd. lll'egnet 300 rotates Ahe har 334iund the trijinl: 213 is connected to the line 319 through the nietliuni of the idle link 80:3.

llf'hen magnet 217 operates it operates reluy 108 in u circuit frein buttery through the Winding' ot Seid relay, sleeve conductor of thetrunl: 100, through conteste of the switch 200, lett Winding' .et muguet 217 to .rou1rcl over conductor 218. Relay 108 locks through its lower Contact to ground the cont ct of relay fr holdingeircuit ie now closed for the magnet 21'? ue follows: battery through both windings oit muguet 21'?, thence through contacte ot the @witch 200 und throng-h `the lower coutuct of relier 100 to ground at the Contact of reL luy 1041-. lteluy 32% is now operated in e circuit :trom buttery through its normal contacte und right Winding', sleeve conductor 2li-0, thence through contacts o1c the switch 200 to the ground d sleeve cou;luctor ot trunl: 100. l -uy 321112 operutee und e locking circuit is con'lpleted` from 4hettery through the iinding of Slow release relay 125, couturt :url .vindinr,v el" relay bZfl to ground over he .electo coruluetor i340.

llhe horuioulul muguet 00 ou the witch 100 is held iu u. circuit jl'roiu hu r"r througru both its4 windings, contarle oit the Switch, Sierre couduetor itl-1 ot the 'truul 213 to ground :it the outer rightcoutectof rele); 325.

The coiuiection hue thus been completed to the cofled lino 2310 und the uppurutuu is uou' reudj. to apply ringing current to siguul the uurted euhscrihef. Before thiu ie donc, hou'cwer, und while the marl-Ier iu stil eeofiuted with the switches, u tout ,ie mudo to determine whether or not the talking circuit which lcuds througrli` contacte of the switch 200 und the Switchlll() is in u, con- 'liuuous condition or 'Whetl'rer there ure :my open pointe therein (luc to uu improper (uwrutiou ot the Switch mutuels. Y For this: purpose u lett relay l if: provided iu the insulter which included iii the reet `rir- `cuit und :idro iu Scrive with the source et telhiugr luztlery ut the rightfhumfl Side ot the repeating coil 100, which relufy operates provided the tullciug circuitis continuous to inform the marker that it muy neleuse und also cuusfe the rcleuee ot `the eender to permit the application of ringing` current. rlhe 'teetcircuit muy he traced from buttery througl-i the :lower ,rilejht whirling' of the leA peu-ting coil 100, winding of relay 105, lower heel: Contact ot relay 107, lower Yfront contact of relay 108thence over the ring Side o1 the trunk, throughv the switch 200, over the ring of the trunk 213, through contacts of the Switch 300 to the ring conductor 342 of the line 310, thence through contacts or' the Switch 300 to conductor 344i of the test link 807, conductor SL10, connector 1002, conductor 1050, connector 900,` conductor 980, Winding of r'eley 731, conductor 031, connector 000, conductor 1031, connector 1002, cconuuctor 347, conductor 841-5 of test link 307, throughcontucts of the Switch 300 to the tip conductor ot line 5319, coutucts of theV s fitcli 300, through the tip conductor of trunk 213, thence through contacts of the switch 200 to the tip conductor of trunk 100, ugper Contact of 'relay 108,upper heck conte t oli reley 107, upper right winding of repeating coil 100 to ground. Assuming that the toet circuit iS continuous, the relay 731 operates und operate., the release relay l0?" in the sender to cuuee the restoretion of Seid sender. The circuit for relay 107 muy he traced from buttery through the i Winding thereof, conductor 425, connector 500, conductor V514:outer Vleft contact ot relay 731, conduct r T37, through the counector 900, conductor 1032, connector' device 1002, conduct r 322, through contacte of the test link to the ySleeve conductor of the line 551,0, thence through. contacts of the su" ch 800 including' horiiioutul link S505 to the .Sleeve conductor l ot the truuk 213 to ground et the outer rigrht coutuct oit relay "3. lteluy 40k" operados :uul loclki4 `to ri uu-:fl ut the coutuct oit rohry /l-ll which.

utter vrelay nu he operated. during the lSetot the regiuters. Relay e507 et itsouter ught front contact opi-brutes the releuue rew luy L00 which releases reluy -11,10, which in turn, releueee relay Ai111. These reluye re- .uiovo the holding' ground potentiel from the ivurioue conductors wliermipou the eender und. souder Selector switch I00 ure restored to normal. Tffhcn relr f" l0? ope lied it opened the circuit oli relay 501, which iu turn, released to cause the release oit relufye 502, 500, 500, S, 50T und Thus, the eender disconnected from the niurlror.

'lho relay 731, iu operating, also operates' the marker relruee relai; B iu uy circuit "iroiu buttery through the winding ot this the verti- .rl 31.6 rufo re stored and the associated bars return' to normal and the connection through the switches is held by the maintained energiaation of the horizontal magnets 217 and 809.

The common marker and controlling equipment including the translatorhas now been restored and may be taken in connection with other calls and the equipment is now ready to apply ringing current to the called subscribers line. l

AtV the time the sender releases vthe eircuit ot relay 101 is opened and this relay again deenergizes. Relay 101 closes an operating circuit for the relay 107 which may be tracedL .trom battery through the outer lett contact of relay 109, winding oi relay 107, contact ot relay 110, inner upper front contact of relay 108, inner upper contact of relay 101, contact of relay 103 to ground. 1t will be noted that relay 103 reoperates in series with the trunk 100 as soon as relay 101 closes its back contacts. Relay 107 operates and ringingcurrent is applied overA the following circuit: troni the ringing source 112, winding of ringing cut-oil relay 110, tlnough the lower front contacts of relays 107 andv 108, thence over the ring side of the subscribei"s line and returning through the upper front contacts oit rela-ys 108 and 107`to ground. called subscriber' answers the ringing cut- Voill relay 110 operates and removing the previously existing shunt permits the relay 109 to operate in the following circuit: battery, through the outer left contact of relay 100, winding ot relay 107, contact and right \\'inding oit relay 100, inner upper contact et relay 108, thence to ground at the contact ot relay 103 as traced. ARelay 109 operates and loclrs and in so doing opens the circuit ot relay 107 which becomes de# energized and the trunk circuit is completed through to the right windings of the repeating coil 100. lt will be noted that the circuit of relay 104 is opened wheny relay 101 lreleases tollowing therelease ot the sender. Relay '104 does not becomeV deenergized to remove ground from the holding conductor, since a new holding circuit is immediately sup plied therefor and may be traced as follows: battery, through the winding oil'Y relay '104, inner lower back Contact of relay 101, le'ft normal contact of relay `100, inner upper front contact of relay 108, inner upper back contact or relay 101 to ground at the contact of relay 108. YVhen the called subscriber answers and relay 100 operates, the

holding circuit for relay 104 is then completed directly to ground at theleiit front Contact of relay 109. lVhen the called party answers the called supervisory relay 105 is operated in the usual manner.

At the end of conversation the parties restore their receivers and relay 103, con# lVhen the Y sequently, becomes released, in turn, releasing relay 109 and relay 104'. Relay 104 r-eleases the relay 108 and removes ground from the sleeve conductor of trunk 100 whereupon the horizontal magnet '217 deenergizes and releases the switch 9.00.

The removal of ground potentional from the trunk 100 also results in the removal of.

ground from the conductor 340, whereupon relays 324 and 325 become vdeener'gized. Relay 325 opens the holding circuit of horizontal magnet 309 which -deenergizes and releases the connector switch 300.

1t will now be assumed that the talking circuit extending through the switches is not continuous at the time the test is made. Therefore, the test relay 731 fails to operate,

since relay 7 31 does not operate neither theV sender nor the marker releases at this time. in order that the marker may not be held up indefinitely, a time measuring` device 744 is provided to count a delinit-e interval ot time within which the marker is allowed to oomplete its functions. VVhenthe marker is first taken for use the relay 745 is operated upon the next closure oi' the upper contact of the device 744. This circuit may be traced from battery through the winding of relay 7 45, normal contact thereof, upper contact of interrupter 744 to ground at the contact of relay 700. Relay 745 locks to the grounded conductorv 713. Upon the next closure ot thelower contact of the interrupter 734, a circuit is completed :tor operate ing the slow releasey relay 704 and may be traced from battery through the winding or" said relay, right'contact of relay 745, outer right contact ot relay 700, lower contact o1' deviceV 744, to the grounded conductor 713. Relay 704`operates the .relay 408 in the sender in a. circuit from battery through thewinding ofrelay 408, conductor 426, connector 500, outer right back contactJ of relay 731 to ground at the inner lett trout contact of relay 704. Relay 408 locks to the grounded Contact of relay 411 and removes ground from conductor 418 to cause the release of the sender connector 500. Relay 408 also lights the trouble lamp 427 whereby the monitoring operator is notilied of the existence of the trouble condition. After having disposed of the trouble the operator may release the sender by operating the key 428 causing the holding relays 411 and 410 to become deenergized.

lVhen relay 704 operates it opens the holding circuit of rcl'ay`700 and the'latter relay releases. Relay 704 locks through its inner right contact, trouble key 7 42 to ground at the outer left contact of said relay. Relay 704 at its left front Acontact also ysupplies a substitute holding ground to the conductor 713 to prevent the release of the marker. The trouble operator may after the source ot the trouble has been located, rc-

store the marker by operating` the key 7112. In case the talking' circuit is continuous at the time the test is made but no ground is connected to the left-hand armatures of .relay 731 due to the open condition of the conductor 7 37 which leads to the test conductors of the swfitch, relay7 408 in the sender does not operate, but relay 405 operates instead after the time measure has counted the interval. The circuit 'tor relay 1105 may be raced 'troni battery through the winding thereof, conductor 430, connector 500, right 'lfront contact of relay 751 to lground at the inner lett front contact of relay 7 04. Relay 05. nicks to ground at the contact oit' holdmit relay 411 and closes a circuit for the trouble lamp 431. Lamp 131 illuminates, .notifying the trouble operator of the nature oit the existing trouble.l

w ln case the called line is busy at the time the test is made, the busy test relay 711 is foperated in the circuit hereinbetore traced. ltelay 711 at its right contact causes the release 'el the operated test relays 720, the mai-'iter connector 900, relay S15, the relay mih'connector 1002, the line vertical manA 'Het 5310, test horizontal magggnet 310 and the vertical magnet The. connection orig'-V inally started is thus wiped out when the called. slioscribers line is found busy.

A riffhen the magnet 212 releases it causes 'the release ot relay 730, which in turn, re-

leases relay 727. Relay 727 again connects tieftest relays 720 to the test conductors leading to the incoming frame 200 for the ipurpose ot determinina` an idle horizontal link to connect the tone apparatus to the incoming,` trunk. VRelay 711y 'closes a circuit lor relay 706 which may be traced from battery, through the winding;` of the latter relayH inner lett contact ot relay 711, outer richt contact o'll relay 730 to ground at the 1er right contactoll relay 700. Relay 706 locks to the conductor 713. Relay 706 operates the magnet 210 ot the incoming selector by means of a circuit from battery through thc winding' of said magnet, thence through the connector 800, lett front Contact of relay 711, inner right contact o'i' relay 706 to the grounded conductor 713. The magnet 210 prepares the contacts in the row 202 which is reserved itor the purpose ,of connecting a tone coil 230 to the incoming` trunks. lilaginet 210, in operating, operates the relay 730 in a manner similar to that discussed in connection with the magnet 212. lclay 7530 operates the relay 728 in a .manner described provided the horizontal link 205 is idle. Relay 72S closes a circuit for operat-l ing` the horizontal magnet 217 as described hereinbet'ore. As soon as the time measurrelays 7 25 and 7a3 `function, the marker battery through the winding of slow release relay 753, back contact olif relay 752, left contact ot relay 7 05 contact of relay 7 06 to gro-und over conductor 713. Relay 753 closes an obvious circuit for relay 752 which operates and loclts to conductor 713. Relay 7 52 opens the circuit of relay 7 53 which releases alter an interval and operates the relay 703 as follows: Battery, through the winding` oit relay 703, inner contactA of relay 7 53, left front Contact of relay 752, left contact or" relay 705, inner right Contact of relay 7 06 to the grounded conductor 713. Relay S causes the release ofthe marker in the manner hereinbefore described. The tone apparatus is now connected to the 'trunk 100 and a busy tone is produced for the purpose ot notifying the calling subscriber that the called subscribers line is busy.' i

llihat is claimed is:

1; In a telephone system, a subscriber-s line, a selective switch having` contacts, means for operating the contacts of said switch to extend a talking` connection to said line, a test circuit .separate from the loop of the subscribers line and inchuling the contacts ol said switch for testing' the condition ot the connection'extended to said line, and means operated when a connection is extended to said line for renderla@` ellective the test circuit.

2. In a telephone system, a subscribefs line, a plurality of selective switches, means for operating said switches to extend a talking connection to said line, a test circuit separate 'from the loop oli' the subscribes line and including the talking conductors of the connection extended through said switches to the subscriber@ line lier testing` the condition or" said connection, and means operated when a connect-ion is extended to the line for rendering said test circuit elifeet-ive.

In a telephone system, a subscribei"s line, a selective switch having contacts, means for operating; the contacts ot said switch to extend a talking,r connection to said line, a test circuit separate from the loop ot' the subscribers line for testing the continuity of the connection extcmled tlirough said switch and means to prevent placing the connection in condition 'lor conversatiou 'if the test reveals that said coiu'xection is not continuous.

l. In a telephone system, a subscribers line, a selective switch, means for operating' the selective switch to extend. a talking connection to said line, a source ot signaling current arranged to be applied to the sub scribers line, a test circuit separate :troni the loop of the subscribes line and including` the contacts of said switch tor testing the condition el. the connection extended thercto, and means controlled by said testing circuit to prevent the application of said source ot signaling current.

In a telephone system, a subscribers line, a trunk circuit having a source of talking current therein, a selective switch for extending said trunk to the subscribers line, means for operating said switch, a test circuit including said source of current 'for testing the connection extended through the switch to said line, and means operated upon the operation of said switch for rendering effective said test circuit. n

6. In atelephone system, a subscribers line, a trunk circuit having a source'of talking current therein, a source of ringing current arranged to be applied to the subscribers line, a selective switch Jfor extend ing` said trunk to the snbscribers line, a marker for controlling the selective operation of said switch, a test circuit including said source of talking' current for testing the connection extended through the switch to the subscribers line, and means in said marker controlled by the test circuitto withhold the application of said source ci ringin g current.

7; In a telephone system, a subscribers line a trunk circuit having a source o't cur- 7 '.f rent therein, a selective switch 'for extending said trunk to the subscribers line, a marker for controlling the operation of said switcii, means for releasing said marker after the operation of said switch, a test circuit including said source of current for testing the connecion extended through the switch to said line, and means controlled by said ref/2,58?

test circuit to prevent the release of said marker.

S. In a telephone, system, a subscriberis line, an automatic switch, means for operating said switch to 'extend a talking connection to said line, a test circuit lseparate from the loop of the subscribers line and including thecontacts of said switch for testing` the continuity of the connection extended to said line, a signal, and means controlled by said test circuit for operating said signal if the extended connection is not continuous.

9. In a telephone system, a subscribers line, a trunk circuit having a source of current therein, a selective switch for extending said trunk to the subscriber-s line, a marker for controlling the operation of said switch, means to release said marker after the operation o'f the switch, a test circuit including said source of current for testing` the connection extended through the switch to the subscribers line, a signal, and means controlled by saidtest circuit to prevent the release of the marker and to render said signal effective.

l0. In a telephene system, a subscribes line, a selective switch havinga plurality 'of links for extending a talking connection to said line, a test link common to said first mentioned links, and a test circuit completed through said test link 'for testing the condition of the connection extended tosiiidv line before said connection is placed in condition for conversation.

In witness whereof, I hereunto subscribe my name this 17th daf,7 of April A. D.,

' SAMUEL B. IVILLIAMS. 

